Our research is aimed at a full understanding of carbohydrate metabolism in the liver and other animal tissues; in a parallel and complementary way we tend to give a biochemical explanation to the related congenital disorders allowing eventually an appropriate treatment. During the next few years, our research will be more specifically oriented to an investigation of the role of fructose 2, 6-bisphosphate in the control of glycolysis and gluconeogenesis in various tissues; we will also try to detect inborn errors of metabolism related to the formation or degradation of fructose 2, 6-bisphosphate. Diseases of peroxysomes and endoplasmic reticulum will also be studied. Liver and muscle biopsies from patients affected by various inborn errors of metabolism (mostly glycogen storage disease, fructose intolerance, galactosemia inborn lysosomal diseases) are regularly received in this laboratory from many clinical centers located mostly in Western Europe but also in South America and other countries. These biopsies will be submitted to both biochemical and ultrastructural investigation. Experimental work on glycolysis and gluconogenesis will be performed on isolated hepatocytes from either rats or other species and also on the brain, pancreatic islets, adipose tissue and yeast. Fructose 2, 6-bisphosphate will be assayed by its property to stimulate PPi:fructose 6-phosphate phosphotransferase. This method allows to determine a fraction of picomole of fructose 2, 6-bisphosphate. The same methodology will be used to measure the two forms of phosphofructokinase 2 and fructose 2, 6-bisphosphatase. All these measurements can be performed on less than 1 mg tissue.